The present invention relates to an information processing apparatus and a memory module. Particularly, the present invention relates to a memory module for generating an internal clock synchronized with an external clock, the memory module being operated based on the internal clock as an operation clock, and to an information processing apparatus having the memory module.
In a notebook type personal computer of recent years, mechanisms by no means inferior to those of a desktop type personal computer, such as a processor capable of high-speed processing and a monitor displaying a sharp and clear image, have been mounted. In connection with this, power consumption required for obtaining desired performance in the notebook type personal computer has been increased, and an extension of a battery lifetime of the notebook type personal computer has become a great subject.
In order to solve such a subject as described above, a graphic processor enabling power saving by selectively using different clock frequencies has been proposed (for example, refer to Non-Patent Document 1). This graphic processor is equipped with a high performance mode operating the graphic processor at a high clock frequency when high performance is required, and with a power saving mode operating the graphic processor at a low frequency by which power saving is realized. The high performance mode and the power saving mode are switched in accordance with a switching action of a user, a switching between an AC mode and a DC mode, and the like.
[Non-Patent Document 1]
Original Internet URL (at the time of this writing) located at: http://www.ati.com/jp/technology/hardware/mobility_fgl—7800/powerplay/
However, in the conventional graphic processor, a graphic memory cannot be operated at a frequency lower than a minimum clock frequency of a DLL circuit thereof. Therefore, the clock frequency of the graphic memory cannot be lowered, and thus it has been impossible to realize sufficient power saving of the graphic processor.